# Delta evolution with sea-level change¶

In this example, we investigate the formation of river-dominated deltas under steady climatic conditions (uniform precipitation) and sea-level fluctuations. Our goal is to reproduced first-order sea-level control on river deltas formation.

The initial surface defines a mount which is a half ellipsoid of 2 km height and a circular diameter of 8 km. The sea-level is initially set at the base of this mount at an elevation of 0 m. A uniform precipitation rate of 1 m/a is applied on the entire area and we test the evolution of the surface and associated deposits due to both hillslope and channel flow. Two diffusion coefficients are defined for the aerial (0.3 m2/a) and marine (0.5 m2/a) environments. The higher value for the marine environment is used to account for sediments reworking by waves and/or currents. The simulation runs for 0.5 Ma and we vary the sea-level through time.

## Initial settings¶

Initial elevation Selevel

For this model, we use the stream power law sediment transport model which scale the incision rate $E$ as a power function of surface water discharge $A$ and slope $S=\nabla z$:

$$E = \kappa A^m (\nabla z)^n$$

where $\kappa$ is the erodibility coefficient dependent on lithology and mean precipitation rate, channel width, flood frequency, channel hydraulics.

The values given to these parameters ($\kappa$, $m$, $n$) need to be set in the XmL input file.

First we initialise the model and set the path to the XmL input file.

You can edit the XmL configuration file at /edit/volume/Examples/delta/delta.xml.

To view the complete XmL options you can follow this link to github page: complete.xml.

In [1]:
from pyBadlands.model import Model as badlandsModel

# Initialise model